2005 GMC Yukon good buy or pass?

Wrong! The Air Bag system with its warning light is totally separate from the Engine Computer and Check Engine light. Neither one will turn on the other one.

The first thing to do is have the exact fault codes read. Many auto parts stores will do that for you for free, but most of the time they can only access the Engine Computer. You'll probably have to find a mechanic with a scanner to read codes in the Air Bag Computer.

We hear too often from a seller that "it's just... ". If they know what's wrong, they would have fixed it, especially if it's just a sensor. You'll want to know exactly what is wrong or have an idea of what it will cost to diagnose the problems before you commit to a price. If the current asking price seems to be really good, there's a reason why. Also ask to see the title before you write a check. If it is listed as a "salvage" vehicle, that doesn't necessarily mean there's anything wrong with it now, but it will reduce its value when you want to sell it. I have a friend with a body shop who specializes in rebuilding less-than-one-year-old smashed Dodge trucks. A lot of them are considered "totaled" by insurance companies because of the cost of labor to do the repairs that's included in the estimates. Some don't even need frame straightening or other structural repairs. In that respect, a salvage vehicle can be a good bargain but to know for sure, have another body shop inspect the repairs.

I am definitely not a fan of GM products but it's not because of the quality of their vehicles. It's because of their extremely customer-unfriendly business practices. Expect to have to go back to the dealer for many of the needed repairs. If you're a do-it-yourselfer, that goes against doing your own work. If you have to run to a mechanic for almost everything, the dealership is usually the best place to go even though in some cases it might cost a little more, so that won't be an issue.

As for the air suspension, you'll have to look on the truck to see if it has that, or ask where you take it for an inspection. Ford is well-known to not make repair parts available after as little as three to five years, so there's a lot of aftermarket systems out there to convert back to regular coil springs. (As a suspension and alignment specialist, I can't tell the difference when I drive a vehicle with air springs). The advantage is the truck should level itself when you're carrying a load. The disadvantage is it adds a lot of cost, complexity, unreliability, frustration, and repair frequency to an otherwise pretty reliable system.

I've driven a car with air suspension, then I ordered the same model with regular coil springs, but I got the rear load-leveling option. That just adds two air shocks and a small module to the rear. The ride quality is exactly the same as with air springs. There are leveling kits you can buy for almost any model if load-carrying becomes an issue.

To address all of these concerns, have the truck inspected at an independent shop, but not one recommended by the seller. There are no common safety issues I'm aware of, but they will look closely at the steering, suspension, and brake systems. They'll "read" the tire wear for signs of an alignment problem. If the truck has anti-lock brakes, you can expect more front wheel speed sensor repairs than for most other brands.

Air bag crash sensors cause very little trouble. In the past the most common cause of the warning light turning on was a broken "clock spring". That's a wound-up ribbon cable in a plastic housing under the steering wheel. A potential clue is the cruise control and / or horn may also not work. With the addition of side air bags and especially explosive charges that tighten seat belts in a crash, those things lead to fault codes for circuits that are more difficult to diagnose, and usually more expensive to repair. Knowing the exact code numbers and descriptions can help us decide on a course of action.

If a seller won't allow you to have the truck inspected, pass, and assume the next person bought a pile of problems. You pick the repair shop(s). An unscrupulous seller could be friends with the people at the shop he recommends, and you will likely not get a fair assessment. Likewise, don't tell the mechanic the name of the seller in case they're enemies. The mechanic may point out things that aren't really serious just to make the seller look bad, or he might give the truck a glowing review so you'll buy it, then be angry with the seller when the problems pop up. You want an impartial opinion. Once you have that, THEN you might mention the seller's name to see if their attitudes change.

A thorough inspection should take about an hour and a half. It will include removing all four wheels, and you should get a fairly detailed list of what was checked. They aren't going to note an intermittent electrical problem or a running problem if they don't act up during the inspection, so you can still be unpleasantly surprised days or weeks later. That can't be blamed on the mechanic. I'm helping a friend right now with a 2006 Equinox that has set a diagnostic fault code for the air pump every two to three months since he bought it three years ago, and no one, including two GM dealers have been able to solve it. That didn't show up on any inspection report. The truck still runs okay, but the problem is with the Check Engine light already on for that problem, you'll never know if a different problem is detected, and often that can be a relatively minor problem that turns serious if it's ignored.

Do not plan on replacing the radio with an aftermarket model. GM built the Body Computer into it so it has to stay in the truck. If you have radio problems, it will have to go through the dealer to one of their two grossly-over-priced repair centers. Replacement computers will also have to come from the dealer and be programmed to the truck by them. You can't use less-expensive used computers from a salvage yard. That's one example of what I meant by "customer-unfriendly" business practices. If you can look beyond that, dandy.